Categorical Data I (collecting and displaying)

Lesson

Categorical data is data that is sorted by groups or categories. Often we look at categories people fit into, such as hair colour, eye colour or gender. However, it doesn't always involve people, types of dogs people own, colours of marbles in a jar or even whether a coin lands on heads on tails are also examples of categorical data.

Let's look now at how we can collect and display categorical data.

1) Decide What Information You're Going to Collect

This is also called a research question. For this example, I want to know what coloured marble is most common in this jar.

2) Construct a Frequency Table

Your frequency table should list all possible outcomes for the experiment you are running. What outcomes are possible in my experiment? Well, there are green, red and blue marbles in the jar- these are all the possible outcomes. My frequency table would look something like this:

Colour Tally Total
Red   7
Green   10
Blue   3

3) Create a graph to display your results

Remember different graphs are suited to different types of data. Bar graphs, column graphs, divided bar graphs or pie charts are good ways to display categorical data. Here is my data displayed in a pie chart.

Now we can clearly see that green is the most common colour of marble in the jar.

Worked Examples

Question 1

The table shows Year 5's answers to the survey question "Do you own a pet?".

What is the best way to display this data?

 Yes 94 16
1. Sector (pie) graph.

A

Line graph.

B

Question 2

Tom took a survey of people's eye colours in his year at school.

1. Complete the table.

Eye Colour Tally Frequency
Brown |||| |||| |||| |||| | $\editable{}$
Black |||| |||| |||| |||| $\editable{}$
Blue |||| |||| || $\editable{}$
Green |||| $\editable{}$
Other |||| |||| |||| || $\editable{}$
2. How many people took part in the survey?

3. What is the rarest eye colour?

Brown.

A

Other.

B

Black.

C

Green.

D

Blue.

E
4. Complete the column graph using the results from the table above.

Question 3

The divided bar graph shows the percentage of each coloured jelly bean in a pack.

1. Which colour jelly bean is the rarest?

Orange

A

Purple

B

Blue

C

Green

D

Red

E
2. Which two colours are equally common?

Blue

A

Green

B

Purple

C

Orange

D

Red

E
3. What fraction of the total jelly beans does the colour Orange represent?